Various publications, including patents, published applications, technical articles and scholarly articles are cited throughout the specification. Each of these cited publications is incorporated by reference herein, in its entirety.
The liver is the largest gland in the body, and plays a vital role in, among other things, digestion, metabolism of carbohydrates, lipids, and proteins, storage of vitamins, minerals, and carbohydrates, production of blood clotting factors, destruction of bacteria in the blood, and detoxification of the body from endogenous and exogenous substances. Given the liver's broad spectrum of functions, diseases and pathologies of the liver can have wide-ranging systemic effects on the body.
One common liver pathology is hepatocellular carcinoma (HCC). HCC ranks fifth of the most common cancers in the world, and is the third leading cause of cancer death (El-Serag H et al. (2001) Hepatology 33:62-5; and, Block T et al. (2003) Oncogene 22:5093-107). The primary etiology for HCC is viral infection, particularly, infection with hepatitis B virus (HBV) and hepatitis C virus (HCV) (Brechot C (1996) Baillieres Clin. Gastroenterol. 10:335-73). HCC can lead to liver cirrhosis. In addition, cirrhosis is a risk factor for HCC (Ikeda K et al. (1993) Hepatology 18:47-53).
Liver cirrhosis is characterized by, among other things, extensive fibrosis, hepatocyte necrosis, collapse of the supporting reticulin network, and extensive deposition of connective tissue. There are multiple etiologies for liver cirrhosis, including viral hepatitis, alcohol abuse, genetics (e.g., Wilson's Disease), venous thromboses in Budd-Chiari Syndrome, and autoimmunity (e.g., Primary Biliary Cirrhosis). Cirrhosis of the liver is irreversible, and if not controlled, can lead to liver failure. In fact, liver cirrhosis is a leading cause of death among adults in the United States, and throughout the world.
It is important that liver diseases such as HCC be detected early in order to provide the patient with the full range of therapeutic options and ultimately improve patient prognosis (Hoofnagle, J H et al. (1997) N. Engl. J. Med. 336:347-56). Furthermore, it is equally important that conditions that predispose to HCC and other liver diseases, for example, cirrhosis, and HBV and HCV infection, be detected early for effective treatment, and for the prevention of the onset of HCC. Unfortunately, many liver diseases, including HBV and HCV infection, can be asymptomatic for many years
In general, liver diseases are diagnosed and monitored by serologic testing, and liver function testing, as well as by physical examination of the patient. In addition, as there is an apparent correlation between elevated expression of alpha-fetoprotein (AFP) and the presence of HCC, screening for AFP is often carried out as a matter of course in cases of suspected liver disease (Buamah P K et al. (1984) Clin. Chim. Acta 139:313-6). However, AFP suffers from several major drawbacks insofar as it can be expressed in the absence of disease, leading to false positive diagnoses, and it is not found to be elevated in up to 50% of liver cancer cases, leading to false negative diagnoses (Nguyen M H et al. (2002) Hepatology 36:410-7). Moreover, the predictive value of AFP substantially diminishes with respect to its capacity to identify early stage HCC (Oka H et al. (1994) Hepatology 19:61-7; Pateron D et al. (1994) J. Hepatol. 20:65-72; and, Zoli M et al. (1996) Cancer 78:977-83).
Thus, more rapid, accurate, and reliable means for the diagnosis of liver diseases that are minimally invasive to the patient, and can be readily and cost-effectively administered to all patients suspected of having liver disease are needed. In addition, there is a need for diagnostic tests that can detect the presence of disease in its incipient or early stages to facilitate effective prophylactic treatment of the patient.